Spiral Network Upgrade Brings Shanghai EVM Equivalence

Ethereum Classic activated the Spiral network upgrade at block 19,250,000 on February 5, 2024, achieving Shanghai execution-layer equivalence. Spiral was specified in ECIP-1109.

## Included EIPs

- **EIP-3651 — Warm COINBASE**: The block producer's address starts in the warm access set, reducing its first-touch cost from 2,600 to 100 gas. Benefits MEV-aware contracts and direct block-producer payments.
- **EIP-3855 — PUSH0 Instruction**: New opcode (0x5f) that pushes zero onto the stack in 1 byte / 2 gas, replacing the previous PUSH1 0x00 (2 bytes / 3 gas). Zero is the most common constant in EVM bytecode, so this reduces deployed contract size network-wide.
- **EIP-3860 — Limit and Meter Initcode**: Caps initcode at 49,152 bytes (twice the EIP-170 deployed-code limit) and charges 2 gas per 32-byte word. Prevents denial-of-service via arbitrarily large initcode payloads.
- **EIP-6049 — Deprecate SELFDESTRUCT**: Formal deprecation notice. The opcode still functions but developers are warned not to depend on its state-clearing behavior. Follows EIP-3529 (Mystique) which already removed SELFDESTRUCT refunds.

## Omitted EIPs

- **EIP-4399 (PREVRANDAO)**: Replaces DIFFICULTY with beacon chain randomness. PoS-only — not applicable to ETC's proof-of-work consensus.
- **EIP-4895 (Beacon Chain Withdrawals)**: Enables validator withdrawals. PoS-only — not applicable.

## Client Requirements

- Core-Geth v1.12.17 or later
- Hyperledger Besu with ETC Spiral support

Spiral represents ETC's current production EVM level, maintaining execution-layer parity with Ethereum while preserving proof-of-work consensus.